The present invention relates to a shock absorber, and more particularly to a nonmetallic gas valve assembly therefor.
Shock absorbers are used in vehicles to dampen inputs from roadways. Conventional monotube shock absorbers include a body which defines a cavity filled with hydraulic fluid. A piston is disposed within the cavity and separates compression and rebound fluid chambers from one another. A rod is secured to the piston to transmit an input force to move the piston within the cavity. A floating piston is arranged in the cavity to separate the compression chamber from a gas chamber. The floating piston moves within the cavity to accommodate the additional volume of the piston rod during the compression and rebound strokes.
A relatively complex gas valve assembly provides for external communication to fill the gas chamber. Conventional gas valve assemblies include a metallic body, an o-ring seal and an internal rubber plug. The metallic body is threaded into the shock body and sealed thereto about the outer periphery through the O-ring. The gas chamber is charged through the gas valve with a needle that is inserted through the plug. The gas chamber is typically pressurized to above 200 psi. When the needle is removed the plug essentially self-seals.
Although effective, the gas valve assembly is a relatively expensive and complicated component. For some vehicle applications, such as snowmobile shock absorbers, such a gas valve may increase the unit cost of the shock absorber considerably.
Accordingly, it is desirable to provide an effective inexpensive monotube shock absorber valve assembly.